gms | German Medical Science

Objective: Maintaining facial nerve function is a major concern in vestibular schwannoma surgery. Despite the routine application of continuous intraoperative neuromonitoring, there is still a risk for a postoperative facial palsy limiting patient’s postoperative quality of life dramatically. So far, facial rehabilitation depends on repetitive voluntary movements accompanied by physiotherapy. However, in the early rehabilitation state active movements are often restricted and, thus, restricting patient’s motivation. In these situations, biofeedback of the facial electromyographic (EMG) signals enables the visual representation of the rehabilitation progress, even without visual movements of the facial muscles. In the present study, we evaluate a custom made EMG biofeedback system enabling cost-effective, home-based rehabilitation of postoperative facial palsy.

Methods: This prospective study enrolled 30 patients with and without a postoperative facial palsy within the first 5 days after surgery. The EMG biofeedback system consisted of Arduino^®-based muscle sensors which were used to record, process and visualize the EMG activity of the affected and unaffected facial muscles on a screen. Finally, recorded EMG activity was correlated to the facial outcome as measured by the House and Brackman (H&B), Facial nerve grading scale 2.0 (FNG2) and the Sunnybrook scale (SUNNY).

Results: Detection of EMG activity was possible in all patients with sufficient quality to operate the biofeedback system. There was a good correlation between EMG activity of the zygomatic muscle and the H&B (r= 0.56; p<0.01) as well as the FNG2 (r= 0.54; p<0.01), respectively. However, there was no significant correlation between the EMG activity of the frontal muscle and these clinical measures.

Conclusion: The present study proves the feasibility of our EMG biofeedback device to detect facial muscle EMG activity in patients with facial palsy after vestibular schwannoma surgery. There is a good correlation between the electrophysiological measurements and the clinical outcome. This EMG activity can be used for home-based facial EMG biofeedback.